Godet roll



Dec. 16:, 1969 55 3,484,581

GODET ROLL Filed June 19. 1967 llmml HEATER CONTROL HEATER POWER SOURCEF/ 2 I INVENTOR.

GORDON L. BLISS his ATTORNEYS Patented Dec. 16, 1969 3,484,581 GODlETROLL Gordon L. Bliss, Uxbridge, Mass, assignor to Whitin Machine Works,Inc, Whitinsville, Mass, at corporation of Massachusetts Filed June 19,1967, Ser. No. 646,937 Int. Cl. B211) 27/06 US. Cl. 219--469 16 ClaimsABSTRACT OF THE DISCLOSURE A godet roll comprising an inner heatersection carrying a helically wound electrical heating coil, which is,preferably, cast in place during the manufacture of the heater section,and a removable outer sleeve received on the heater section. Thetemperature coefiicient of expansion of the heater section is greaterthan the outer sleeve, and the parts are dimensioned so that the sleevecan be slid relatively easily onto the heater section at ambienttemperature but is held in place by an interference fit at operatingtemperature. A temperature sensor in the form of a resistance wire iswound helically around the heating section and is preferably located atthe interface between the heating section and the outer sleeve at thezone of the roll where the material being treated leaves it.

BACKGROUND OF THE INVENTION This invention relates to a novel andimproved godet roll.

In the manufacture of synthetic yarns, the synthetic fiber-formingmaterial is extruded as a multiplicity of filaments, and the filamentsare brought together and drawn. The drawing step is extremely importantin the process because it determines, to a considerable extent, themechanical properties of the yarn.

One type of drawing apparatus usedin the manufacture of synthetic yarnscomprises a series of rolls called godet rolls. The yarn as it comesfrom the extruding device first makes a multiplicity of turns around afirst stage of preheating godet rolls, which are rotating at arelatively slower speed, and then a multiplicity of turns around a stageof draw godet rolls, which operate at a relatively higher speed. In theprocess of transferring from the slower rolls to the faster ones, theyarn is pulled or drawn. In addition, it is given a heat treatment onthe second stage rolls or a subsequent, third stage.

The necessity of maintaining the rolls at critical temperatures and ofoperating them at relatively high speeds creates a number of problems.Although a number of godet rolls of various constructions have beenproposed each has one or more shortcomings. For example, one type ofgodet roll is composed of a rotating, bell-shaped roll which is heatedfrom an annular, fixed heating unit received within the roll. The heattransfer in this type of roll is extremely poor, and the ability tocontrol the temperature of the roll, particularly where the ambientconditions vary, is minimal. In another form, a solid roll is providedwith circumferentially spaced-apart, longitudinally extending cartridgeheating elements. Al though the heat transfer is significantly improvedby providing the heat elements on the roll body, this form has adisadvantage of a lack of uniformity of temperature circumferentiallyaround the surface of the roll. Moreover, refurbishing of the rollsurface, being an integral part of the roll, is difficult andtime-consuming.

SUMMARY OF THE INVENTION The foregoing and other disadvantages of godetrolls of the types previously suggested in the art are overcome, inaccordance with the invention, by a novel and improved godet rollembodying a number of features that provide better heat transferefficiency, the ability to achieve and maintain precise temperaturecontrol from a point remote from the roll, roll temperature uniformity,ease of roll surface refurbishing with a minimum of down time, and otherimproved characteristics. More particu larly, the godet roll of theinvention comprises a heater section in the form of a generallycylindrical member, preferably of a material having high thermalconductivity, a heating element that rotates with the roll, andpreferably encased within the heater section and forming a part of it,and an outer removable shell received on the heater section. Thetemperature coefficient of expansion of the heater section is greaterthan that of the outer sleeve, and the parts are dimensioned so that thesleeve can be slid relatively freely onto the heater section at ambienttemperatures, but an interference fit is obtained at operatingtemperatures to securely hold the outer sleeve on the heater section.

In a preferred embodiment, the godet roll is heated by a rod-typeelectrical heating element that is helically wound, with respect to. theroll, and is preferably cast in place during the manufacture of theheater section. The temperature of the roll is controlled by aresistance wire sensor wound helically on the heater section, preferablyat its periphery and thus the interface between the outer sleeve and theheater section. The roll includes a hub for cantilevering it from theshaft of a drive motor, and both the heating coil and the resistancewire leads are led through the motor shaft and are brought out through aslip ring to the temperature controller and the power source for theheater. The controller may be located at a point remote from the roll,such as in a main control console for the draw machine.

The heater section of the roll may be composed of an inner tubularmember and a body portion which is cast using the inner shell as onemold part. Keepers for the electric heating element are attached to theinner shell prior to casting the heater section body and facilitateprecisely locating the coil in the cast body to ensure heatinguniformity.

The resistance wire heat sensor coil preferably occupies acircumferential band of fairly substantial width say, on the order ofone quarter of the length of the roll, thereby providing a temperaturemeasurement that is an average of a relatively large amount of surfacearea of the roll. The band occupied by the heat sensor coil may, toadvantage, be located in the region of the point where the yarn leavesthe roll, because the maximum temperature of the yarn as it leaves theroll is normally the best indicator of the overall heating. A furtherimportant advantage of a resistance wire heating control is that it isnot sensitive to noise occurring at a slipring, inasmuch as it draws afairly large current. Moreover, the resistance of the element isproportionate to the temperature, thus providing a relatively largecontrol range. Moreover, the resistance wire sensor can be used athigher operating temperatures than other types of sensors, especiallythermistors.

The invention offers numerous advantages. For one thing, the efficiencyof heat transfer provided by mounting the heating coil for rotation withthe roll surface is markedly better than in rolls in which the heatingcoil is fixed and is separate from the rotating roll. Heat transferefiiciency is further enhanced by the interference fit at operatingtemperature between the sleeve and the heater section, the tightness ofthe sleeve on the heater section ensuring good contact and thus goodheat transfer at the interface between the sleeve and heater section.The helical form of heating element considerably facilitates providing auniform temperature about the circumference of the roll. Moreover, itprovides for a predetermined temperature gradient longitudinally alongthe roll surface, a desired gradient being obtainable by varying thepitch of the helix as required to increase or decrease the degree ofheating of any given circumferential section of the roll. The resistancewire temperature sensor, as mentioned above, provides excellenttemperature detection, inasmuch as the effect of noise at the slip ringis negligible; moreover, the location of the sensor element over afairly broad range of the roll provides an average value that is notsusceptible to isolated variations. The construction of the roll,notably the relatively thin outer shell, facilitates locating thetemperature sensor very near the roll surface, and preferably near thepart of the length of the roll where the yarn leaves the roll, and it istherefore possible to employ the sensor not only as an element of theheater controller but also as a monitor of the operation of the roll,the resistance element forming a part of a measuring circuit providing ameter reading or a recorded value of temperature at all times during theoperation of the roll.

The construction of the roll in two parts, namely the heater section andthe outer sleeve, and using materials having different temperaturecoefficients of expansion makes it possible to replace the outer sleevequickly and easily; this is of considerable advantage, inasmuch ascostly down time for refurbishing the roll is kept at a minimum.Furthermore, the overall construction of the roll permits locating itscenter gravity relatively close to the motor and thus facilitatesdesigning and balancing for higher operating speeds. The roll can bekept down to a relatively low weight, a further advantage for high speedoperation. Preferably, the heater section body is formed of castaluminum which offers the advantages not only of light weight but highthermal conductivity, and where the heater section is composed of twoparts, the inner part may be steel which provides the strength neededfor a high speed roll and also facilitates joining the roll to the shaftby means of a hub welded to the inner shell of the heater section. Apreferred embodiment of the roll also includes cooling fins on the hubcarrying the roll, thus inhibiting the heating of the shaft and thebearing in which the shaft is joumaled.

DESCRIPTION OF THE DRAWING For a better understanding of the invention,reference may be made to the following description of an exemplaryembodiment, taken in conjunction with the figures of the accompanyingdrawing, in which:

FIG. 1 is a pictorial view showing, generally schematically, the overalllayout of the godet roll, the drive motor and the heater control; and

FIG. 2 is a side view in cross-section, the section being takengenerally at a diametrical plane of the roll and only a part of thedrive motor being shown.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Referring first to FIG. 1, thegodet roll, which is designated generally by the reference 10, isadapted to be mounted at one end of the shaft 12 of a motor 14. At theopposite end of the motor shaft 12 is a slipring unit 16 having foursliprings (not shown), two for connecting motor is shown in FIG. 1schematically as being supported by a rigid horizontal surface, it isappropriate to mount the motor in any suitable manner on a frame and 4in back of a panel (not shown), the roll 10 being mounted in front ofthe panel.

Referring next to FIG. 2, which shows the construction of the roll 10and adjacent parts of the motor in more detail, the motor 14 includes anend bell 40 having a protective cover 41 attached to it and carrying abearing 42 which in turn supports the motor shaft 12. Near the end ofthe shaft 12 is a tapered portion 12a which receives a hub 44 on theroll 10. The hub 44 is formed with an annular flange 44a carrying a heatsink in the form of a ring 46 having a plurality of outwardly extendingcooling fins 48, the ring 46 being secured on the flange 44a by means ofset screws 49. The hub also has an outwardly extending flange 44b havinga series of cooling fins 440 formed in its rear surface. The fins 46 and44c remove heat from the hub 44 and thus inhibit the heating of theshaft 12 and lower the operating temperature of the bearing 42. The hub44 is secured to the shaft by means of a nut 50 threaded onto a threadedportion 12b at the end of the motor shaft 12.

The cylindrical body of the roll 10 is composed of a heater section 54and an outer shell or sleeve 56 received on the heater section. Theheater section 54 consists of two parts, an inner shell 58 which ispreferably made of stainless steel and is joined by weldments 60 to theoutwardly projecting flange 44b of the hub 44, and a body portion 62surrounding the inner shell 58. The inner shell 58, as shown in thedrawings, has a tapered wall thickness, the taper being in a directionmoving away from the hub 44, but this feature is a matter of choice. Thebody 62 is preferably aluminum and is cast in place around the shell 58,the shell 58 serving as one mold part, and then machined to dimension.The material of the shell 58 and body 62 should have temperaturecoefficients of expansion of approximately the same magnitude in orderthat the thermal expansion does not cause the body 62 to become loosenedon the shell 58.

The heat source for the roll 10 is a rod-type electric heating element64 which is cast in place in the body portion 54. Prior to casting thebody portion, the heating element is wrapped helically around the innershell 58 and is located and held in position by slots 66a incircumferentially spaced-apart keepers 66 (of which only one is shown)which are welded or otherwise suitably attached to the outer surface ofthe shell 58. Advantageously the free ends 64a of the heating element 64are brought in and connected to lead wires 68 and 69 located atdiametrically opposite positions near the outer end of the shell, withrespect to the motor, the heating element being wrapped in a doublehelix leading from the terminal points back toward a point near the hub44 where a 180 bend 64b occurs. The lead wires 68 and 69 are connectedto terminals 70 and 71 of an electrical coupling 72 that is threadedinto the endportion 12b of the motor shaft 12. The shaft 12 has an axialbore 120 carrying a cable 74 connected to and leading from the coupling72 back through the motor and into the slipring unit 16 (FIG. 1).

Because the heating element 64 wraps helically around the heatersection, temperature uniformity in the circumferential direction isensured. A desired temperature gradient in the lengthwise direction canbe established, to a point, by varying the pitch of the helix asdesired. On the other hand, the pitch cannot exceed a certain value,depending on the dimension from the sleeve outer surface to the heatingelement, without creating alternate hotter and cooler circumferentialbands along the length of the roll.

The heater section 54 also carries a heat sensing element in the form ofa resistance wire coil 78 installed in a helical groove 80 machined inthe outer surface of the heater section body portion 62. The resistancewire coil extends over a circumferential band of relatively substantialwidth, say on the order of A of the total length of the roll 10, and islocated adjacent the outer end of the roll 10. As will be describedbelow, the yarn processed on the roll is led in adjacent the inner endof the roll (the end nearest the motor 14) and takes several turnshelically outwardly along the roll where it leaves near the outer end.Thus the resistance wire coil is located in a region of the roll wherethe yarn leaves it. The ends of the resistance wire coil 78 are broughtin through the shell 58 and connected to terminals 82 and 83 of thecoupling 72 by leads 84 and 85 which are in turn coupled by means of thecable 74, the slipring unit 16, and leads 24 and 26 to the heatercontrol 28 (FIG. 1).

The outer sleeve 56, which is preferably made of stainless steel and ischrome-plated, has a circumferential head or flange 56a at its innerend, with respect to the motor 14, and an end cover 88 joined, such asby welding, to its outer end, the end cover and therefore the sleevebeing fastened by screws 90 to the body portion 62 of the heater section54. Although the screws 90 serve to mount the outer sleeve 56 on theheater section 54 at ambient temperature, the primary means by which itis held on is by an interference fit established at operatingtemperature upon expansion of the parts of the roll 10.

More particularly, the material selected for the sleeve 56 has atemperature coefiicient of expansion that is somewhat less than thetemperature coefiicient of expansion of the materials of the heatersection 54, and the heater section and sleeve are dimensioned so thatthe shell 56 can be slid onto the outer surface of the heater sectionbody 62 at ambient temperature. Upon heating, however, the heatersection expands to a greater extent than the sleeve, thus bringing itinto firm engagement with the sleeve and providing an interference fitbetween them.

The construction of the roll 10 in two parts, or more precisely in threeparts, provides a number of significant advantages. First of all, theweight of the roll 10 is kept at a minimum without sacrificing strength,the heater section inner shell 58 and the outer sleeve 56 being of steeland providing strength and the body 62 being of aluminum and providinghigh thermal conductivity and low weight. Further, the constructionfacilitates the installation and replacement of the shell surface,should the need arise, thus making it unnecessary to replace an entireroll in the event of damage to its surface. Moreover, the outer shell 56may have a relatively low wall thickness, thus making it possible tomanufacture it without particularly high roundness tolerancerequirements since it will conform to match the shape of the body 54upon installation. The efficiency of heat transfer in the roll 10 isenhanced by the fact that the major part of the heat-conducting pathfrom the heating element 64 to the surface of the roll 10 is through thealuminum or other high thermal conducting material, the outer shellbeing, as mentioned above, relatively thin. The center of gravity of theroll 10 is relatively near the inner end of the roll (with respect tothe motor 14) thus, in conjunction with the light weight of the roll,making it better adapted for high speed operation.

In operation, two rolls of the type illustrated in the drawing arenormally used together, being spaced apart and mounted with their axesslightly out of parallel so that the yarn, which makes several turnsaround them and spans the space between them, is fed from the inner endsof the rolls toward the outer ends. The roll surfaces are kept heated toa closely controlled temperature by controlled energization of theheating coil 64 from the heater power source 22, the power to the coilbeing proportional in response to signals through the conductors and 32received from the heater control 28. The heater control 28, in turn,receives signals proportionate to the roll temperature, via theconductors 24, 26, the slip ring unit 16, the cable 74, and leads 84 and85, from the resistance wire coil 78. It will be noted that thetemperature sensor is, as mentioned above, located at the interfacebetween the heater section 54 and the outer sleeve 56 of the roll and atthe region of the roll where the yarn leaves it. Accordingly, thetemperature detected by the sensor 78 is closely related to thetemperature of the yarn as it leaves the roll. Moreover, it is anaverage value taken over a relatively large section of the roll. Theloca tion and coverage of the sensor 78 provide rapid response and veryaccurate control. In practice, the temperature of the roll can bemaintained within a fraction of degree of a predetermined desiredtemperature. Moreover, the indication of temperature yielded by thesensor 78 can also be used as a monitor value and the current (which isindicative of the resistance) applied to a meter or recorder to give acontinuous reading or record of the roll temperature.

Replacement of the sleeve 56, should it become damaged, is accomplishedquickly and easily when the roll is at ambient temperature by removingthe screws holding the end cover 88 on the heater section and simplypulling the shell and cover longitudinally off the end of the heatersection 54. Upon sliding a replacement sleeve 56 in place and installingthe screws, the roll is ready for operation, and reheating of the roll10 to operating temperature automatically creates an interference fitbetween the shell and heater section upon their thermal expansion.

The above-described embodiment of the invention is intended to be merelyexemplary, and those skilled in the art will be able to make numerousvariations and modifiations of it without departing from the spirit andscope of the invention. All such variations and modifications areintended to be included within the scope of the invention as defined inthe appended claims.

I claim:

1. A godet roll comprising an inner heater section in the form of amember having a cylindrical outer surface and carrying heating meansrotatable with the roll, and an outer removable cylindrical sleevereceived on the heater section, the temperature coefficient of expansionof the heater section, being greater than that of the sleeve such thatthe sleeve is slidable onto the heater section at ambient temperaturebut is in interference fit with the heater section at the operatingtemperatures of the roll.

2. A godet roll according to claim 1 wherein the heating means comprisesa rod-type electrical heating element wound helically with respect tothe heater section.

3. A godet roll according to claim 2 wherein at least part of the heatersection of the roll is cast of a highly heat conductive material, andwherein the electrical heating element is embedded in the cast part bybeing cast in place.

4. A godet roll according to claim 1 further comprising a temperaturesensor in the form of a resistance wire wound on the heater sectionmember helically with respect to the roll about a band of substantialwidth relattive to the longitudinal dimension of the roll.

5. A godet roll according to claim 4 wherein the band occupied by theresistance wire temperature sensor is disposed in the region of the rollwhere the product treated by the roll leaves the roll.

6. A godet roll according to claim 1 further comprising a shaft-mountinghub carrying the heater section and sleeve, the hub having cooling finsfor removing heat from the hub and inhibiting the heating of a shaftcarrying the roll.

7. A godet roll according to claim 3 wherein the heater section furtherincludes an inner shell within the cast part, the shell and cast parthaving temperature coefiicients of expansion of the same order ofmagnitude to ensure against separation at the interface between themupon heating.

8. A godet roll comprising a drive motor having a shaft, a slip ringunit at one end of the motor and receiving the motor shaft, acylindrical roll structure cantilevered from the other end of the motorshaft, the roll structure having an inner heater section in the form ofa cylindrical member carrying heating means rotatable with the rollstructure, and an outer cylindrical sleeve received on the heaterstructure, an electrical conductor cable extending through the motorshaft and coupled to the slip ring unit and including first conductorelements coupled to the heating means, a heater power source coupledthrough the slip ring unit and the said first elements of the conductorcable to the heating means, a resistance wire temperature sensor carriedby the roll structure and rotatable with it and coupled to secondelements of the cable, and heater control means connected through theslip ring unit and the said second elements of the cable to thetemperature sensor for controlling the heater power source to maintain apredetermined temperature of the roll structure.

9. A godet roll according to claim 8 wherein the temperature coefficientof expansion of the heater section is greater than that of the sleevesuch that the sleeve is slidable onto the heater section at ambienttemperature but is in interference fit with the heater section at theoperating temperatures of the roll.

10. A godet roll according to claim 8 wherein the heating meanscomprises a rod-type electrical heating element Wound helically withrespect to the heater section.

11. A godet roll according to claim 10 wherein at least part of theheater section of the roll is cast of a highly heat conductive material,and wherein the electrical heating element is embedded in the cast partby being cast in place.

12. A godet roll according to claim 8 wherein the temperature sensor isWound helically with respect to the roll about a band of substantialwidth relative to the longitudinal dimension of the roll.

13. A godet roll according to claim 12 wherein the band occupied by theresistance wire temperature sensor is disposed in the region of the rollwhere the product treated by the roll leaves the roll.

14. A godet roll according to claim 8 further comprising a hub carryingthe roll structure and mounted on the motor shaft, the hub havingcooling fins for removing heat from the hub and inhibiting the heatingof the shaft.

15. A godet roll according to claim 11 wherein the heater sectionfurther includes an inner shell within the cast part, the shell and castpart having temperature cefiicients of expansion of the same order ofmagnitude to ensure against separation at the interface between the uponheating.

16. A godet roll comprising an inner heater section having an innershell, a shaft-mounting hub joined to one end of the shell to receive adriving shaft for the roll, a body portion surrounding the sleeve castfrom a highly heat conductive material and a rod-type electrical heatingelement wound helically within the body and around the inner shell andbeing embedded in the body by being cast in place, the shell and body ofthe heater section having temperature coefficients of expansion of thesame order of magnitude; a thin-wall cylindrical sleeve surrounding theheater section and formed of a material having a temperature coefficientof expansion less than the temperature coefiicient of expansion of theinner shell and body of the heater section such that the sleeve isslidable onto the heater section at ambient temperature but is ininterference with heater section body at the operating temperatures ofthe roll; and a resistance wire temperature sensor coil wound helicallyonto the heater section body and occupying a circumferential band ofsubstantial width in the region of the roll Where the product treated bythe roll leaves the roll.

References Cited UNITED STATES PATENTS 839,343 12/1906 Vogel 338--2323,227,857 1/1966 Hill et a1 2l9469 3,296,418 1/ 1967 Johnson 2l94693,355,784 12/1967 Beyers et a1. 2l9469 3,286,081 11/1966 Scowcroft2l9469 3,257,939 6/1966 McDermott 2l9469 FOREIGN PATENTS 264,755 10/1963 Australia.

GEORGE HARRIS, Primary Examiner FRED E. BELL, Assistant Examiner

